Metallocene-catalyzed polymerization of ethylene in the presence of graphite. II. Structure and electrical properties of the composites

Structure and electrical properties of conducting polyethylene/graphite composites have been studied in relation to the preparation method, i.e. (i) the polymerization-filling technique (PFT), in which the polyolefinic chains are growing from the graphite surface, (ii) the slurry polymerization of ethylene in the presence of untreated graphite, and (iii) the mechanical blending of preformed polyethylene and graphite. The extent of the filler dispersion depends on the method used for the composite preparation. Moreover, the graphite particles can be oriented by the molding of the samples used for the measurement of the electrical properties. This orientation is as pronounced as the melt viscosity of polyethylene is low, this characteristic feature changing with the preparation method. These structural details have consequences on the electrophysical properties and the percolation threshold. Finally, the thermal dependence of the electrical resistivity has been studied.